function recombineTagsAndDecorations()

in content/resources/js/prettify.js [1062:1156]
69 lines of code
15 McCabe index (conditional complexity)

    function recombineTagsAndDecorations(job) {
        var isIE = /\bMSIE\b/.test(navigator.userAgent);
        var newlineRe = /\n/g;

        var source = job.sourceCode;
        var sourceLength = source.length;
        // Index into source after the last code-unit recombined.
        var sourceIndex = 0;

        var spans = job.spans;
        var nSpans = spans.length;
        // Index into spans after the last span which ends at or before sourceIndex.
        var spanIndex = 0;

        var decorations = job.decorations;
        var nDecorations = decorations.length;
        // Index into decorations after the last decoration which ends at or before
        // sourceIndex.
        var decorationIndex = 0;

        // Remove all zero-length decorations.
        decorations[nDecorations] = sourceLength;
        var decPos, i;
        for (i = decPos = 0; i < nDecorations;) {
            if (decorations[i] !== decorations[i + 2]) {
                decorations[decPos++] = decorations[i++];
                decorations[decPos++] = decorations[i++];
            } else {
                i += 2;
            }
        }
        nDecorations = decPos;

        // Simplify decorations.
        for (i = decPos = 0; i < nDecorations;) {
            var startPos = decorations[i];
            // Conflate all adjacent decorations that use the same style.
            var startDec = decorations[i + 1];
            var end = i + 2;
            while (end + 2 <= nDecorations && decorations[end + 1] === startDec) {
                end += 2;
            }
            decorations[decPos++] = startPos;
            decorations[decPos++] = startDec;
            i = end;
        }

        nDecorations = decorations.length = decPos;

        var decoration = null;
        while (spanIndex < nSpans) {
            var spanStart = spans[spanIndex];
            var spanEnd = spans[spanIndex + 2] || sourceLength;

            var decStart = decorations[decorationIndex];
            var decEnd = decorations[decorationIndex + 2] || sourceLength;

            var end = Math.min(spanEnd, decEnd);

            var textNode = spans[spanIndex + 1];
            var styledText;
            if (textNode.nodeType !== 1  // Don't muck with <BR>s or <LI>s
                // Don't introduce spans around empty text nodes.
                && (styledText = source.substring(sourceIndex, end))) {
                // This may seem bizarre, and it is.  Emitting LF on IE causes the
                // code to display with spaces instead of line breaks.
                // Emitting Windows standard issue linebreaks (CRLF) causes a blank
                // space to appear at the beginning of every line but the first.
                // Emitting an old Mac OS 9 line separator makes everything spiffy.
                if (isIE) { styledText = styledText.replace(newlineRe, '\r'); }
                textNode.nodeValue = styledText;
                var document = textNode.ownerDocument;
                var span = document.createElement('SPAN');
                span.className = decorations[decorationIndex + 1];
                var parentNode = textNode.parentNode;
                parentNode.replaceChild(span, textNode);
                span.appendChild(textNode);
                if (sourceIndex < spanEnd) {  // Split off a text node.
                    spans[spanIndex + 1] = textNode
                        // TODO: Possibly optimize by using '' if there's no flicker.
                        = document.createTextNode(source.substring(end, spanEnd));
                    parentNode.insertBefore(textNode, span.nextSibling);
                }
            }

            sourceIndex = end;

            if (sourceIndex >= spanEnd) {
                spanIndex += 2;
            }
            if (sourceIndex >= decEnd) {
                decorationIndex += 2;
            }
        }
    }